Pond Snails: Mostly Good…. Sometimes A Sign of Problems

   

Hello all…..

 

Your friendly neighborhood Freshwater Biologist here with a special report on pond snails.  

 

Aquatic snails are generally fantastic.  These members of the Mollusk family serve the ecosystem near the bottom of the food chain, consuming organic material (plant matter mostly) and going about their business (slowly….cuz they’re snails) of making more snails.  The species that live in the Midwest are mostly small (about the size of your thumbnail) and truck around down in the rocks and sediments looking for stuff to eat.

 

Aquatic snails are an abundant food source for a multitude of organisms, providing a great source of energy for the critters that prey upon them.  There are some invasive species trying to wiggle into their niche (I’m looking at you, zebra mussels), but as a whole, the pond snails are in good shape population-wise.

 

Now, the dark side of pond snails……..

 

There is a creature in our midst that is the bane of lounging aquatic humans just about everywhere.  Swimmer’s Itch.  This vile organism causes sizable purple welts that produce an unholy itch the rival of which I have not encountered in this life.  I believe the correct anatomical term is an inflammatory immune reaction. These welts last more than a week (about a month in my case), and are generally the worst….just the worst!

 

What’s this have to do with pond snails?

 

Well, snails are an intermediate host for the little parasitic bast…..uh… critters.  Swimmer’s itch is a flatworm that needs an aquatic snail as a host for a portion of its lifecycle.  It encounters humans when it’s looking for its final host, a duck.

 

The incidence of swimmer’s itch increases as the pond snail population increases.  Therefore, if you see many snails in your pond or lakeshore, it is likely that swimmer’s itch resides there too.  I find that occurs in highly organic sediments most frequently. So, wherever there is organic soft sediment (muck), beware.  

Here is the lifecycle of swimmer’s itch as provided by the CDC.

What do you do if you know you have swimmer’s itch in your waterbody? One thing is to reduce the number of snails in your area.  That is, reduce their available habitat and food sources. I recommend two strategies to reduce muck in order to revitalize your shoreline habitat and reduce the rearing areas for swimmer’s itch.

 

I recommend beneficial bacteria products that eat away at the goo, greatly reducing the total volume of sediment and improving near shore habitat.

 

Here are a few products that I like:

 

Kasco Macrozyme Bacteria.

AirMax Pond Logic Muck Away

 

Another way to remove the muck that the snails live in is to physically remove it from the premises.  The easiest way to accomplish this is with a watermover. Installing a watermover at the end of your dock or pier will greatly reduce the organic soft sediment, improve fish habitat, and clear any floating debris from around your shoreline.

 

The best units I’ve found are these:

 

Scott Aquasweep (also available with an oscillator for even better results)

Kasco Circulators

 

Another means of managing swimmer’s itch is to kill it off.  This will only work in small areas as it is not feasible to treat large lakes.

 

This is a last resort option.  The products that are effective will have to be used at maximum label dosages and have other deleterious effects to the ecosystem.  There are no products labeled for use against the organism responsible for swimmer’s itch. There are, however, algaecides that are effective in killing the organism.  The active ingredient (copper sulfate penthydrate) is lethal to many small organisms (bacteria, algae, many others) and it can also kill the larval stage of our favorite flatworm.

 

NOTE: This is a non-label use of an aquatic pesticide.  You should follow all of your local laws and ordinances when applying it to mitigate any downstream effects. I recommend hiring a certified applicator to help you apply this product.  The brand I use is called Earthtec.  these treatments will be small scale and temporary…. In some cases it’s the only way to stem an infestation in a small lagoon or lake frontage.

 

Anyhoo, I hope I have helped you understand this particular scourge a little better. Thanks again for taking the time to read my articles.  If you have any questions or comments, please feel free to comment or contact me through Midwestponds.com.

 

JOE CADIEUX
Senior Biologist
Midwestponds.com

 

Fountain Aerators Vs Diffused Aerators

Hello friends…..

I get many questions every week as to the nature of fountains vs diffused aerators.  They are different, they perform different tasks, and most often it matters witch one you choose…..

FOUNTAINS:

All fountain manufactures (and I do mean ALL FOUNTAIN MANUFACTURES) market their products as aerators. They are correct in the abstract, but fall short in the task of true whole pond aeration.

By definition, the aeration of water is the agitation of surface water or the infusion of atmospheric air (or oxygen) into the water column.  So yeah, they do aerate the water.  The difference is in how they do it and their effectiveness in doing so.  Aerating fountains have been the staple management tool for fish hatcheries world wide for half a century.  They will aerate the water column and keep your fish happy and healthy.

Fountains float on the surface of the water and shoot water into the air creating a fantastic display, and most times they even have lights attached to enhance the experience at night (fountain)(lights).  I do love me my fountains, they truly enhance the pond atmosphere and cancel out traffic noise and do turn some air into the pond.  They are very good at forcing floating debris, algae, and plants like duckweed to the edges of the pond where they can be more easily removed/treated.

For best management results: these units are best suited for ponds that are 4-5ft deep (or less).  Fountains can only suck water from around where they are floating, so you are only mixing the water within the first 3-4ft of water depth.  For systems deeper than 4-5ft and larger than 7000 square feet you need a diffused aeration system.

DIFFUSED AERATION:

Sub-suface diffused aeration systems are comprised of an air compressor, airline, and diffusers.

The diffusers sit on the bottom of the pond and “diffuse” billions of bubbles witch rise to the surface.  The overall size of the pond determines how many diffusers you will need to adequately turn over the pond.

Diffused air does more than just inject oxygen into the water, it also removes the bad dissolved gasses (methane, ammonia, nitrous oxide, sulfur dioxide) as the oxygen moves out of the bubbles and into the water, these bad gases move in and are carried to the surface where they blow away on the wind.  The surface area of the bubbles also grab all of the water around them and lift it to the surface.  This effectively turns the pond over and exposes the nutrient rich water from the bottom to the atmosphere, releasing even more bad gases and turning in more air.  These systems also are necessary for the degradation and decomposition of organic soft sediment (muck) as they provide oxygen to the bottom sediments allowing for the bugs and microbes to consume the organic material.  Example of a good system (here)

So, long story short…… If you are looking to turn some water and have a beautiful display…… the Fountain is the way to go.

If you are looking to manage an aquatic ecosystem, and help the overall health and longevity of a pond the diffused aeration system is the correct option.

If you desire both…. well then by all means, install them together and enjoy your pond for years to come.

Thanks so much for reading….. please contact me if you want some clarification or a more in depth review of these systems.  CSJ&J Gardens and midwestponds.com 833-779-2837.

JOE CADIEUX
Senior Biologist